1. Field of the Invention
The present invention relates to an electronic endoscope system having a main light source and an auxiliary light source.
2. Description of the Related Art
A high intensity lamp, such as a halogen lamp, a mercury vapor lamp or a metal halide lamp is used as a main light source of a light source apparatus for an electronic endoscope. If the light source goes off due to expiration of the service life thereof or trouble during examination or an operation using an endoscope, it is necessary to replace the light source or the light source apparatus with a new one. It is not desirable for the endoscope to stay in a body cavity of a patient during replacement of the light source.
To solve this problem, it has been proposed to provide a separate auxiliary light source in addition to a main light source made of a high intensity lamp, wherein if the main light source goes off, the auxiliary light source is used to illuminate a body cavity of a patient, so that an insertion portion of an endoscope can be entirely removed from the body cavity under the illumination by the auxiliary light source (see Japanese Patent Applications Laid-open Nos. 2000-210245, H10-108826, 2002-72106).
As the auxiliary light source is provided for emergency use and is seldom used, it is preferable that the auxiliary light source be as small as possible and tend not to deteriorate due to aging. To this end, for example, a high intensity LED can be used.
However, if the auxiliary light source is a high intensity LED, the amount of light emitted therefrom is smaller than that of the main light source, and hence, there is a possibility, during use of an electronic endoscope, that a picked-up image is too dark due to insufficient amount of light emitted from the auxiliary light source.